Change BKPT and UDF encodings on ARM.

src/trusted/service_runtime/arch/arm/sel_ldr_arm.h

 /*
  * Copyright (c) 2012 The Native Client Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SERVICE_RUNTIME_ARCH_ARM_SEL_LDR_H__
 #define SERVICE_RUNTIME_ARCH_ARM_SEL_LDR_H__ 1
 
 #include "native_client/src/include/portability.h"
 #include "native_client/src/trusted/service_runtime/nacl_config.h"
 
 /* NOTE: we hope to unify this among archtectures */
 #define NACL_MAX_ADDR_BITS      30
 
 #define NACL_ADDRSPACE_LOWER_GUARD_SIZE 0
 #define NACL_ADDRSPACE_UPPER_GUARD_SIZE 0x2000
 
 #define NACL_THREAD_MAX         8192  /* arbitrary, can be larger */
 
 #if defined(NACL_TARGET_ARM_THUMB2_MODE)
 #define NACL_NOOP_OPCODE        0x46c0      /* mov r8, r8 */
 #define NACL_HALT_OPCODE        0xbe00      /* bkpt 0x0000 */
 #define NACL_HALT_LEN           2           /* length of halt instruction */
 #else
 #define NACL_NOOP_OPCODE        0xe1a00000  /* mov r0, r0 */
-#define NACL_HALT_OPCODE        0xe1266676  /* bkpt 6666 */
+#define NACL_HALT_OPCODE        0xE7FEDEFF  /* UDF #0xEDEF */
 #define NACL_HALT_LEN           4           /* length of halt instruction */
 #endif  /* defined(NACL_TARGET_ARM_THUMB2_MODE) */
 #define NACL_HALT_WORD          NACL_HALT_OPCODE
 
 #endif /* SERVICE_RUNTIME_ARCH_ARM_SEL_LDR_H__ */